A method of delivering data timely between periodic tasks in a distributed real-time system

摘要

The invention relates to a method for the time-correct data transfer between cyclic tasks in a distributed real-time system, which real-time system comprises a real-time communication system and a multiplicity of computer nodes, wherein a local real-time clock in each computer node is synchronised with the global time, wherein all periodic trigger signals zib for the start of a new cycle i are derived in each computer node simultaneously from the advance of the global time, wherein these periodic trigger signals start the tasks, and wherein a task reads the output data of the other tasks from local input memory areas, to which the real-time communication system writes, and wherein a task writes the result data of the current cycle to a local output memory area, which is associated with the communications system, at an a priori determined individual production instant zif before the end of a cycle, and wherein the schedules for the time-controlled communication system are configured such that the result data of a task present in the local output memory area is transported to the local input memory areas of the tasks requiring the data during the time interval zif, zi+1b, so that at the start of the following cycle this result data is available in the local input memory areas of the tasks that require this result data.